Fluid drain valve



May 17 1960 A. J. LECHNER ErAL 2,936,773

FLUID DRAIN VALVE n Filed Jan. 25, 1957 FE. le

INVENTORS ALBERT J. LECHNER GUILFORD W. LOUTHAN Aggnt Y FLUID DRAIN VALVE Albert J. Lechner, North Hollywood,`and Guilford W.

Louthan, Van Nuys, Calif., assignors to Lockheed Aircraft Corporation, Burbank, Calif.

Application January 2s, 1957, serial No. 636,426 9 Claims. (cpl. 137-204) This invention relates generally to uid ow control valves and more particularly to an automatic uid drain valve for pressurized enclosures such as the fuselage of aircraft.

' In sealing off an enclosure to provide an efficient pressure vessel, uid leakage from equipment carried inside the enclosure and moisture produced by condensation are trapped and must be periodically drained. This is conventionally done in aircraft, for example, through the use of manually operated drain valves. lf the.ground crew fails to open the drain valve periodically, Ythe waste uids are retained in the aircraft. If the ground crew fails to close the drain valvethe pressurization system is overworked due to air leakage throughthe valve opening. Thus, a drain valve which'will. automatically close in response to pressurization of the enclosure and which will automatically open when the enclosure is depressurized offers many advantages` over a drain valve of the manual type. However,.an automatic uid drain valve suitable for use in a pressurized enclosure such 'asl the fuselage of an aircraft must meet certain standardsof performance not required of a manual valve. The valve must be light in weight and above all, dependable in operation. The Working parts of the valve should be protected so that damage will not result from personnel stepping on the valve or dropping cargo thereon. The valve should have a high iiow rate and permit access of fluids to the drain hole from substantially all directions for complete drainage. Furthermore, valve` actuation must be effected at a pressure differential which is less than that at which the pressurized enclosure is intended to operate. In aircraft usage, the drain valve shouldbe actuated in response to a pressure differential of approximately one p.s.i. or less.

It is an object of this invention to Aprovide a drain Valve for pressurized enclosures which will automatically close in response to pressurizing the enclosure and automatically open in response to depressurizing the enclosure. By proper design of the disclosed valve construction, valve actuation may be effected at'dilferential pressures of the order of 0.5 p.s.i.

Another object of this invention is to provide an automatic iuid drain valve whichis constructed to utilize the valve supporting structure for guarding the Working parts of the valve and to providea high flow rate with maximum access of liuids to the drain hole.

Another object of this invention is to provide an automatic uid ydrain valve which may be economically produced and easily installed and maintained.

Still another object of this invention is to provide an automatic uid drain valve which is dependable in operation and which will substantially eliminate leakage through the drain hole at all differential pressures above that required for valve closure. v y

considered in combination with thev accompanying draw-l ins wherein like, numerals, refer t0K like. Parts- 2,936,773 Patented May 1 7, 1960 still another modified form of sealing element for the automatic uid rdrain valve.

Referring to Figures 1 and 2 the valve inccludes a y generally U-shaped bracket 10 having lianges 11 and 12 which seat against the inner surface 13 of wall member 14, the 'latter representing a pressurized enclosure such as the fuselage of an aircraft. Bracket 1li is suitably secured interiorly of the enclosure such as by bolts 15 eX- tending through wall member 14 and flanges 11 and 12.

Bracket 10 spans an opening 16 formed in enclosure wall member 14 and yieldingly supports a resilient sealing element or disk 17 generally concentricv with the opening through the use ofqa leaf spring 18. The leaf` spring, as shown in Figure l, is secured at one end 19 to the bridge portion 20 of bracket 10 by bolts 21 or the like. Two acute angle bends formed in leaf spring 18 positions the free end 22 of the spring over opening 16 and in a plane generally parallel with the plane of the wall at the opening. Sealing element 17 is suitably secured to free end 22 of spring 18 such as by vulcanizing. Sealing element 17 may be molded from rubber or any other resilient material which is capable of deforming under the applied pressure when the valve is closed, to effect positive contact with enclosure wall member 14 continuously around the opening.

Bridge portion 20 may extend outwardly forming an overhang 28'on. either end of bracket 10 to provide adequate protection for leaf spring 18.

Leaf spring 18 should be at least as wide as opening 16 so that adequate support will be provided for resilient sealing element 17 topreveut the same from warping under the internal pressures effecting closure of the valve.

VAlso the radius of curvature of the acute angle bends in leaf spring 18 should be selected so that sealing element 17 in the open position of the valve is in the neighborhood of 1A to 1A inch from enclosure wall member 14 depending upon the specific design requirements.

The plan form size of sealing element 17 must of course be greater than thevplan form 'size of opening 16 to effectively seal the opening. The cross-sectional shape of sealing element 17 is preferably as shown in Figures l and 2 wherein a continuous bead 23 is formed on the outer periphery thereof so that contact with wall member 14 around opening 16 is first made by the bead when the valve closes. This localizes the closing forces and provides'high contact pressures around the opening for preventing fluid leakage at low differential pressures.

There areseveral modifications which may be made to the preferred form of sealing element 17 without departing from the teachings of the invention. One such modification is illustrated in Figure 3 wherein sealing element 17 is secured' to the free end of leaf spring 18 by extruding a grommet-like detent 24 on the sealing element through an opening 25 formed in the leaf spring. Furthermore, in the Figure 3 configuration the seating surface 26 of the sealing element is at with no continuous bead being formed thereon as shown in the configuration of Figures 1 and 2.

A second modification of the sealing element is illustrated in Figure 4 wherein a simple O ring seal 27A is squeezed between enclosure wall member 14 and the leaf spring the opening is completely sealed. In function, O ring 27 is indentical to bead 23 formed on sealing element 17 in Figures 1 and 2.

In operation, when the enclosure is depressurized so that the pressures both inside and outside of the enclosure are substantially equal, sealing'element 17 is suspended above opening 16 by spring 18 allowing any waste iluid within the enclosure to drain through opening`16. When the enclosure is pressurized so that the internal pressure is -greater than the external pressure the pressurizing ilurd starts to How through opening 16 creating a pressure drop byv venturi action which is addedto thenormal pres-V sure differential existing between the inside and the outside of the enclosure. By the proper selection of leaf spring 18 and by supporting sealing element 17 approximately Ms to 1A inch from wall member 14 of the. enclosure, actuation of-the valve to close opening 16 may be .effected at differential pressures even less than 0.5 p.s`.r. As the sealing element` is vforced into engagement with enclosure wall member 1011k as illustrated by dotted lines in Figure l, the resiliency of the sealing elementV provides a uid tight seal even though a poorly mating seating surface is provided by-wall member 14 andy even though solid particles might be caught between the sealing element and its seating surface on the wall member. The higher the dilferential pressure the greater is the force maintaining the valve closed.

As the diierential pressure is decreased, thevalve will .remain closed until Vthe force exerted by the differential pressure is less than the force exerted by spring 18 tending to raise the sealing element to the open position. This threshold value for the differential pressure is substantially the same or slightly lower than the threshold value of the differential pressure required to close the va ve.

Valve operation is substantially the same with any of the three sealing elements shown. Normally the use of a bead or its equivalent has the effect of slightly increasing the differential pressure required to close the valve as compared with a flat sealing element as shown in Figure 3, however, it is substantially more effective in preventing uid leakage at low pressure differentials due to the higher contact pressure between the sealing element and the seating surface on enclosure wall member 14 around opening 16. Y

While the preferred embodiment of the valve employs a leaf spring because of its high resistance to movement in all directions except toward and away from the valve opening, it should be understood that other types of springs may be employed within the teachings of the in- Ventron. Accordingly, it should be understood that certain alterations, modifications and substitutions such as those suggested hereinabove may be made to the instant disclosure without departing from the spirit scopefof" the invention as dened by the appended claims.

We claim:

l. In a pressurized enclosure, an automatic uid drain valve comprising, a wall member serving as a part of the enclosure and having an opening formed thereinV through which fluid may drain, a bracket secured to the wall member and spanning the opening, a leaf spring secured at one end to said bracket and having at least one acute angle bend therein, the free end of said spring extending transversely over the opening between the bracket and wall member, and a resilient disk generally aligned with the opening and secured to the free end of said spring, said spring supporting said disk spaced from the Vopening for movement toward the opening inl response to a pressure dierential whereby the disk is deformably pressed against the wall member sealingrfthe opening only whenthe enclosure is pressurized.

42. In a pressurized enclosure, an automatic' fluid drain Vassenza 1 wall member adjacent' the opening, a spring secured at one end to said bracket and extending outwardly therefrom and in the general direction: of theV opening, the free end of said spring terminating inspaced relation with the openinggand a resilient disk carried on the free end of said spring for movement toward the opening in response to a pressure differential whereby the disk is deformably pressed against the wall member sealing the opening only when the enclosure is pressurized.

4. In a pressurized enclosure, an automatic duid drain valve as defined in claim 3 including a continuous bead secured to the resilient disk generally concentric with the opening for engaging the wall member when the valve is closed.

5. In an `aircraft having `a pressurized enclosure, an automatic uid flow control valve comprising, a wall member serving as a part of the enclosure and havingV an opening formed therein through which fluid may drain, a bracketsecured to the wall member on thek inside thereof and spanning said opening, a leaf spring secured at one end to said bracket and having at least one acute angle bendV formed therein, the free end of said spring extending transverselyV over the opening between the bracket and wall member, and a resilient sealing element secured to the free end of said spring and arranged generally concentric with the opening, said spring yieldingly supporting said sealing element spaced from the opening whereby the valve is responsive toV pressurization of the enclosure for actuation to close the opening by deformably pressing the disk against the wall member.V

6.,A device as defined in claim Shaving a continuous bead secured to the sealing element for engaging the wall member around the opening when the valve is closed.

7. In a pressurized enclosure, anV automatic iiuid drain valve comprising, a wall member serving as'a part of the enclosure and having an opening formed therein through which uid may drain, a resilient sealing element having a platform size greater than the size ofV the opening, and spring means carried within the enclosure and supporting said sealing element for movement toward and away from the opening in response to a pressure differential whereby the sealing element is valve as defined in claim 1 including :acontinuous beadY 75 deformably pressed against the wall member sealing-the opening only when the enclosure is pressurized.

S. In a pressurized enclosure, an automatic fluid drain valve comprising, arwall member serving as part of the enclosure and having an openingformed therein through which liruid may drain, abracket secured to the wall member and spanning the opening, a leaf Vspring secured:

at one end thereof to said bracket, and a resilient sealing element secured to the opposite endof said leaf spring and generally aligned with the opening whereby pressurization of the enclosure eiects movement ofthe. sealingl means yieldingly supporting` said sealing member spacedl from the opening whereby the valve is responsivev to pressurization of the enclosure" for moving the sealingelement into'engagement withy saidI wall member-to deform and matetherewith,*and a continuous bead formed on at least one of said members for engaging the other 2,563,200 Venning Aug. 7, 1951 member around said opening when the valve is closed. 2,599,622 Folmsbee June 10, 19752 v Y 2,655,936 Wexler et al.' Oct. 20, 1953 References Cited in the le of this patent 2,719,531 sogg@ Oct, 4, 1955 UNITED STATES PATENTS 5 2,793,649 Hamer May 28, 1957 756,869 Manseld Apr. 12, 1904 i FOREIGN PATENTS 978,152 Gutermuth Dec. 13, 1910 18,175 Great Britain Aug. 13, 1906 2,217,380 Pedder et al. Oct. 8, 1940 16,483 Great Britain July 18, 1907 

